Recompute an invoice exactly and report where it disagrees with itself
Recompute an invoice exactly and report where it disagrees with itself. Quantity times unit price is an exact decimal product. Rounding happens only where the stated policy says: per line, or once on the whole invoice. Those give different totals, so the difference between the two policies is published rather than one being assumed correct. Also reports a figure with more decimal places than its currency has, and a discount larger than its line.
Answeringour last check, 2026-10-04
1 of 1checks answered this week
4844 msmedian answer time
$0.22listed price per call
$0.22price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
POST https://api.zfinia.com/x402/v1/invoice-arithmetic-audit
| Category | Code and developer |
|---|---|
| Provider host | api.zfinia.com |
| Networks | eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 1 from 1 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-10-04 | valid payment request | 402 | $0.22 | 4844 ms |
Example input (from the provider)
{
"body": {
"invoice": {
"currency": "AUD",
"id": "INV-7781",
"lines": [
{
"description": "Widget",
"line_total": "59.97",
"quantity": "3",
"tax_amount": "6.00",
"tax_rate": "10",
"unit_price": "19.99"
},
{
"description": "Washer",
"line_total": "7.03",
"quantity": "7",
"tax_amount": "0.70",
"tax_rate": "10",
"unit_price": "1.005"
},
{
"description": "Service call",
"discount": "120.00",
"line_total": "-20.00",
"quantity": "1",
"tax_amount": "-1.82",
"tax_rate": "10",
"unit_price": "100.00"
}
],
"subtotal": "47.00",
"tax_total": "4.88",
"total": "51.88"
},
"policy": {
"round_per_line": true,
"rounding": "half_up",
"tax_inclusive": false
}
},
"bodyType": "json",
"method": "POST",
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"additionalProperties": false,
"properties": {
"invoice": {
"additionalProperties": false,
"properties": {
"currency": {
"maxLength": 8,
"type": "string"
},
"id": {
"maxLength": 128,
"type": "string"
},
"lines": {
"items": {
"additionalProperties": false,
"properties": {
"description": {
"maxLength": 512,
"type": "string"
},
"discount": {
"type": [
"string",
"number"
]
},
"line_total": {
"type": [
"string",
"number"
]
},
"quantity": {
"type": [
"string",
"number"
]
},
"tax_amount": {
"type": [
"string",
"number"
]
},
"tax_rate": {
"type": [
"string",
"number"
]
},
"unit_price": {
"type": [
"string",
"number"
]
}
},
"required": [
"quantity",
"unit_price"
],
"type": "object"
},
"maxItems": 500,
"minItems": 1,
"type": "array"
},
"subtotal": {
"type": [
"string",
"number"
]
},
"tax_total": {
"type": [
"string",
"number"
]
},
"total": {
"type": [
"string",
"number"
]
}
},
"required": [
"currency",
"lines"
],
"type": "object"
},
"policy": {
"additionalProperties": false,
"properties": {
"minor_units": {
"type": "object"
},
"round_per_line": {
"type": "boolean"
},
"rounding": {
"enum": [
"half_up",
"half_even",
"down",
"up"
],
"type": "string"
},
"tax_inclusive": {
"type": "boolean"
}
},
"type": "object"
}
},
"required": [
"invoice"
],
"type": "object"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
},
"method": {
"enum": [
"POST"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}